Many different types of rotary hammer mills are found in the art employing reversible or readily replaceable grate bars or sections. Typical of early structures are found in the patents issued to:
______________________________________ PATENTEE PATENT NO. ______________________________________ Albrecht 604,283 Borton 759,856 Armstrong 1,170,389 Williams 1,420,355 ______________________________________
In Anderson, U.S. Pat. No. 1,746,512, an improved grate bar is described which has a rectangular cross-section with spaced lugs extending therefrom, which together with like grate bars, forms an overall grate having reversible features. Grate bar assemblies having various improvements in terms of ease of reversibility, increased structural strength, and more ready accessability are also shown in one or more of the following patents.
______________________________________ PATENTEE PATENT NO. ______________________________________ Williams 3,465,973 Greiffenstern 3,813,045 Miller 4,015,783 Whitney 4,061,277 ______________________________________
In spite of the great amount of prior art in this field, there remains a real need for (1) a more readily available access means to both the grate assembly structure and hammers so that the various components of both grate and hammers can be readily replaced or reversed as the need arises, and (2) for a grate assembly structure which coacts with the hammers of the hammer mill to achieve more efficient size reduction of material.
It will be understood that because of the tremendous impact forces acting upon the grate assembly by virtue of the high speed rotation of the hammers as they reduce, by shear, crushing, etc. metallic materials such as auto bodies, small motors, ores, slags, solid wastes, and the like, there is a great need for an extremely efficient means for obtaining rapid access and entry to both the grate system and the hammers of the hammer mill to replace worn parts, or to reverse certain grate components to present fresh shearing surfaces--all for the purpose of maintaining, as closely as possible, the optimum dimensional relationship between hammers and grate assembly, with minimum down-time, for a wide variety of materials ranging from municipal wastes to fractional horsepower motors. Related to the overall aim of this invention is the use of a more efficient grate system, than has been heretofore contemplated, permitting more efficient size reduction of such a great variety of materials.
It is a major object of this invention to remedy the above-described deficiencies of the prior art.